Grasslands GAR Outline Revised 10 16 2015 conjunctively involve reuse of tile drainage to ......

Outline for

Groundwater Quality Assessment Report

Grassland Drainage Area

October 16, 2015

Prepared for

San Luis and Delta‐Mendota Water Authority

Prepared by

Grassland Drainage Area GAR Outline 1

Outline for Groundwater Quality Assessment Report

Grassland Drainage Area

The Grassland Basin Drainage Steering Committee (Steering Committee) serves as the third-party group for growers within the Grassland Drainage Area (GDA) (Figure 1). The Waste Discharge Requirements (WDR), General Order R5-2015-0095, which applies to growers within the GDA, were adopted by the Central Valley Regional Water Quality Control Board (Board) on July 31, 2015. The approval date associated with the WDR starts the timeline for several requirements, including the requirement for submittal of a Groundwater Quality Assessment Report (GAR). In advance of preparing the GAR, the WDR also specifies that, 90 days after Order approval from the Board, the Steering Committee “will provide a proposed outline of the GAR to the Executive Officer that describes the data sources and references that will be considered in developing the GAR.” (Attachment B, Monitoring and Reporting Program [MRP]). Accordingly, we understand that the due date for submittal of the Groundwater Quality Assessment Report (GAR) outline is October 29, 2015.

This GAR Outline presents the general structure to be followed in the GAR and also includes a table of potential data sources, a preliminary bibliography, and a table that cross references the GAR outline with the requirements contained in the WDR. The preliminary bibliography provides references that may be used during preparation of the GAR, although not all included references will necessarily be used and additional references are likely to be added. Similarly, not all of the data sources listed will necessarily be used, and additional sources are likely to be added. Numerous figures and tables are anticipated in the GAR; these are not explicitly identified in the Outline.


1. INTRODUCTION

a. Background

i. San Luis and Delta-Mendota Water Authority

1. Grassland Basin Drainage Management Activity Agreement

2. Grassland Basin Drainage Steering Committee (Grassland Committee)

ii. Waste Discharge Requirements and Other Timelines

b. Purpose of Groundwater Quality Assessment Report (GAR)

c. Grassland Drainage Area

i. Central Valley Floor (extent of DWR Bulletin 118 groundwater basins/subbasins, specifically Delta-Mendota Groundwater Subbasin 5-22.07)

1. Grassland Drainage Area (GDA), approximately 97,400 acres

ii. Overview of high salinity in shallow groundwater

1. Tile drain system

a. Order covers discharge to groundwater not captured by tile drains

b. Grassland Bypass Project (GBP) and San Joaquin River Water Quality Improvement Project (SJRIP)

c. Relation of perched water table to protected groundwater (i.e., degree of hydraulic communication)

iii. SJRIP reuse area and use of salt tolerant crops

2. PHYSICAL SETTING

a. Location

i. Topography (Source: USGS Digital Elevation Model)

ii. Climate (Source: CIMIS and NCDC weather stations)

iii. Surface Water

iv. Tile drains in relation to perched water table.

v. San Joaquin River Water Quality Improvement Project and Grassland Bypass Project conjunctively involve reuse of tile drainage to irrigate salt tolerant plants and transport of subsurface ag drain water (not surface tail water) in Grassland Bypass Channel (GBC) to San Luis Drain, bypassing wetland habitat areas).


b. Geologic Setting (Sources: Geologic and hydrogeologic data from published reports, including USGS Central Valley Hydrologic Model (CVHM); existing maps and relevant cross-sections; DWR Bulletin 118 basin/subbasin information)

i. General Hydrogeologic Setting

ii. Natural Surface Water and Groundwater Chemistry

iii. Physical Conceptual Model

1. Very Shallow Unconfined Groundwater (water table aquifer)

2. Semi-Confined Upper Aquifer (above Corcoran Clay)

3. Corcoran Clay

4. Confined Lower Aquifer (below Corcoran Clay)

5. Hydrogeologic Conceptualization

c. Surface and Subsurface Sediments Characterization

i. Surficial Soils (Sources: Natural Resources Conservation Service (NRCS), CVHM, soil and soil surface characteristics, including soil permeability and chemistry and surface slope and drainage characteristics; map(s) of soils)

1. Soil Hydraulic Conductivity

2. Soil Drainage (Source: tile drain information [GDA Districts, USBR, DWR], published literature)

3. Soil Chemistry (including soil salinity and alkalinity)

ii. Hydraulic Properties of Subsurface Sediments (Sources: CVHM, published literature)

1. Very Shallow Groundwater Zone

2. Upper Aquifer

3. Corcoran Clay

4. Lower Aquifer

5. Subsurface Sediment Texture

3. Groundwater Hydrology i. Groundwater Levels (Sources: DWR, USGS, USBR, SWRCB GeoTracker,

GDA districts, other local entities)

1. Groundwater Level Dataset

2. Development of Groundwater Level Contours (various time periods)

3. Spatial Patterns in Depth to Groundwater (spring and fall depth to groundwater; very shallow depth to groundwater compared to depths representing semi-confined and/or confined conditions)


4. Groundwater Flow Directions

5. Temporal Groundwater Level Trends (primary focus on shallow groundwater)

a. Shallow wells

b. Deep wells

ii. Recharge to Groundwater (Sources: existing publications; special attention to potential for recharge upgradient of existing public areas for urban and rural communities)

1. Recharge Areas Upgradient of Public Water Systems Reliant on Groundwater (including any rural and/or Disadvantaged Communities)

2. Drained Areas

4. LAND USE

a. Lands within the Grassland Drainage Area

i. Irrigated Agriculture Lands

ii. Non-Irrigated Lands

iii. Managed Wetlands

1. Private Wetlands

b. Available Data Describing Land Use and Extent of Irrigated Lands (Sources: DWR, USDA, USBR, UC Cooperative Extension, GDA Districts; several snapshots of historical to more recent land use, pending data availability)

i. DWR Land Use Data

ii. USDA Land Use Data

iii. GDA Districts’ Land Use Data

c. Land Use Categorization

d. Land Use Change

e. Predominant Commodities

i. Based on current, available land cover information; particularly commodities representing the top 80% of irrigated agricultural crops

f. Irrigation Practices (Sources: GDA districts, DWR land use surveys, UC Cooperative Extension, USDA)

i. Irrigation practices generally associated with predominant commodities (as presently known and available)

g. Fertilization Practices (Sources: CDFA, UC Cooperative Extension, published literature)


i. Fertilization methods and soil amendments generally associated with predominant commodities (as presently known and available)

h. Nitrogen Cycle

i. Common Application Methods and Use for Primary Commodities

5. GROUNDWATER QUALITY

a. Groundwater Quality Dataset (Sources: GDA districts, USBR, DWR, USGS, GAMA Domestic, CDPH, SWRCB GeoTracker GAMA, RWQCB Dairy, Department of Pesticide Regulation, County Health Dept. data for domestic wells (or other wells, as readily available))

i. Data used in the evaluation will incorporate the best available location coordinates as provided through publicly available online resources or the best available information provided by the above entities

ii. Well information may be limited to that typically provided by the above entities (i.e., such information as well construction may not be readily available for many of the above datasets)

iii. Locations of water systems and/or wells serving disadvantaged communities will be obtained as available

b. Historical Presence of High Salinity in Shallow Groundwater (Sources: Datasets as noted above, published literature)

i. Sources of salinity (naturally occurring and other; broad overview of historical salinity; legacy effects)

ii. Mechanisms contributing to increased salinity

c. Spatial Patterns in Groundwater Quality (focus on nitrate, TDS, and pesticides; upper and lower parts of aquifer system)

i. Nitrate Concentrations

ii. TDS Concentrations

iii. Pesticides

1. Detections

2. Exceedances

iv. Boron and Selenium

d. Temporal Trends in Groundwater Quality (focus on nitrate and TDS; evaluated separately for upper and lower parts of aquifer system, as possible from available data)

i. Time-Series Nitrate Concentrations

ii. Notable Temporal Trends in Nitrate Concentrations


iii. Time-Series TDS Concentrations

iv. Notable Temporal Trends in TDS Concentrations

e. Additional Groundwater Quality Data (Sources: published literature)

i. Summarize selected constituents (related to irrigated agriculture) other than nitrate, salt and pesticides that exhibit elevated concentrations (e.g., above a drinking water standard as applicable) such as trace metals (selenium), other cations or anions, etc.; these data would be summarized based on readily available published reports. These would be reconnaissance level summaries.

f. Summary of Groundwater Quality Data

6. GROUNDWATER VULNERABILITY AND PRIORITIZATION

a. Overview of Groundwater Vulnerability Assessment

i. Previous Assessments of Groundwater Vulnerability in the Grassland Drainage Area

1. SWRCB Hydrogeologically Vulnerable Areas

2. DPR Groundwater Protection Areas

3. Other Evaluations of Potential for Groundwater Contamination

b. Grassland Drainage Area Groundwater Vulnerability Approach

i. Conceptual Model

1. Shallow Unconfined Groundwater and Upper Aquifer (above Corcoran Clay)

a. Salinity conditions

b. Nitrate conditions

2. Confined Lower Aquifer (below Corcoran Clay)

a. Salinity conditions

b. Nitrate conditions

3. Variable role of Corcoran Clay as barrier to vertical movement of nitrate (depending on depth and thickness)

ii. Groundwater Quality in the Context of the Physical Conceptual Model

1. Comparison of trends in salinity and nitrate concentration by aquifer

a. Salinity and nitrate concentration trends in wells in the shallow unconfined groundwater (pending data availability)

b. Salinity and nitrate concentration trends in wells above Corcoran Clay (upper aquifer)


c. Salinity and nitrate concentration trends in wells below Corcoran Clay (lower aquifer)

d. Salinity and nitrate concentration trends in relation to properties of the Corcoran Clay (e.g., presence, depth, thickness)

2. Approach to Assessing Groundwater Vulnerability

iii. Statistical Analyses of Associations between Observed Water Quality and Physical Hydrogeologic Conditions (Variables)

1. Groundwater Quality Characteristics Variables (Dependent Variable)

2. Hydrogeologic Variables of Interest (Independent Variables)

3. Accounting for Land Use and Agricultural Practices

iv. Description of Statistical Analyses

1. Assumptions

2. Data Investigation and Statistical Analyses

v. Multiple Regression Results

1. Hydrogeologic IndependentVariables

a. Soil hydraulic conductivity

b. Depth to groundwater

c. Corcoran Clay properties

d. Topographic slope

e. Well depth

f. Groundwater recharge

g. Subsurface texture

h. Other potential variables of interest

2. Non-Hydrogeologic Variables of interest

a. Date

b. Land use and agricultural practices (as currently known and available)

3. Multiple Regression Equation Development

4. Multiple Regression Results and Diagnostics

vi. Groundwater Vulnerability Model Evaluation and Characterization

vii. Comparison of Groundwater Vulnerability to Groundwater Quality Conditions in the Grassland Drainage Area


1. Nitrate

2. TDS

3. Pesticides

4. Other Water Quality Constituents of Interest

viii. Summary of Grassland Drainage Area High Vulnerability Area

c. Prioritization of High Vulnerability Area

i. Prioritization Calculation Approach

1. Matrix with Values Assigned to Criteria (below are examples of the criteria)

a. Consideration of existing groundwater quality observations especially exceedances of water quality objectives (e.g., nitrate exceeding the MCL)

b. Consideration of historical groundwater quality and trends (improving groundwater quality, declining groundwater quality, rate of trends, including rate of trends for wells that exceed half the nitrate MCL)

c. Proximity of high vulnerability areas to areas contributing recharge to urban and rural communities that rely on groundwater; water systems and/or wells serving disadvantaged communities will be considered pending the availability of information that identifies such systems or wells

d. Consideration of constituent toxicity and mobility

e. Existing operational practices identified to be associated with irrigated agricultural waste discharges (i.e., practices as currently known and available).

f. The largest acreage commodity types comprising up to at least 80% of the irrigated agricultural acreage in the high vulnerability areas and the irrigation and fertilization practices employed by these commodities (i.e., irrigation and fertilization practices as currently known and available).

ii. Identified Priority Areas

iii. Summary of Prioritization


7. GROUNDWATER MONITORING PROGRAMS

a. Sources of Information on Existing Groundwater Monitoring Programs

i. DWR/CASGEM

ii. State Water Resources Control Board

iii. USGS

iv. CDPH

v. DPR

vi. RWQCB – Dairy Monitoring Programs

vii. GAMA

viii. USBR

ix. GDA Districts

x. Grassland Basin Drainers

xi. Groundwater Management Plans (e.g., Southern Agencies in the Delta-Mendota Canal Service Area (2009), Westside-San Joaquin Integrated Water Resources Plan (2014), others as available)

b. Summary of Existing Groundwater Monitoring Programs

i. Recent Monitoring Programs ii. Overview of Data Gaps (Identify key data gaps for wells in existing

monitoring programs (e.g., well construction information, accurate spatial coordinates, constituents analyzed, etc.))

iii. Potential Monitoring Well Candidates (i.e., potential existing monitoring wells for future Trend Monitoring purposes (availability of construction information, distribution of wells, availability to access, etc. to be assessed as part of Trend Monitoring Workplan))

iv. Area participates in CASGEM through the San Luis & Delta-Mendota Water Authority

8. REFERENCES


Preliminary Bibliography1 AECOM. 2019. Groundwater Management Plan for the Southern Agencies in the Delta-Mendota

Canal Service Area. Aller, L., T. Bennett, J. H. Lehr, R.J. Petty, and G. Hackett. 1987. DRASTIC: A standardized

system for evaluating ground water pollution potential using hydrogeologic settings: NWWA/EPA Series, EPA-600/2-87-035, U.S. Environmental Protection Agency, Robert S. Kerr Environmental Research Laboratory, 455 p.

Anning, D.W., A.P. Paul, T.S. McKinney, J.M. Huntington, L.M. Bexfield, and S.A. Thiros.

2012. Predicted nitrate and arsenic concentrations in basin-fill aquifers of the southwestern United States: U.S. Geological Survey Scientific Investigations Report 2012-5065.

Antonakos, A.K., and N.J. Lambrakis. 2007. Development and testing of three hybrid methods

for the assessment of aquifer vulnerability to nitrates, based on the drastic model, an example from NE Korinthia, Greece, Journal of Hydrology, Vol. 333, 288 p.

Belitz, K. and J. H. Frederick. 1990. Character and evolution of ground-water

flow system in the central part of the western San Joaquin Valley, California. U.S. Geological Survey Water-Supply Paper 2348.

Belitz, K., S.P. Phillips, and J.M. Gronberg. 1993. Numerical simulation of ground-water flow in

the Central Part of the western San Joaquin Valley, California: U.S. Geological Survey Water-Supply Paper 2396, 69 p.

Belitz, K. and S.P. Phillips. 1994. Simulation of water-table response to management

alternatives, Central part of the western San Joaquin Valley, California: U.S. Geological Survey Water-Resources Investigations Report 91-4193, 41p.

Belitz, K. and S.P. Phillips. 1995. Alternative to agricultural drains in California’s San Joaquin

Valley: results of a regional-scale hydrogeologic approach: Water Resources Research, Vol. 37, No. 8, 1845-1862 p.

Bennett, G.L., K. Belitz, and B.J. Milby Dawson. 2006. California GAMA Program -

Groundwater quality data in the northern San Joaquin basin study unit, 2005: U.S. Geological Survey Data Series 196, 122 p.

Bertoldi, G.L., R.H. Johnston, and K. D. Evenson. 1991. Ground water in the Central Valley,

California – A Summary Report. U.S. Geological Survey Professional Paper 1401-A. 1 This is a preliminary list of potential references that may be used during the preparation of the Groundwater Quality Assessment Report. Not all of the references shown at this time will necessarily be used. Other references may also be added.


California Department of Pesticide Regulation. 2000. Depth to groundwater database. http://www.cdpr.ca.gov/docs/emon/pubs/ehapreps/eh0002.pdf.

California Department of Pesticide Regulation. 2013. Ground Water Protection Area shapefiles.

http://www.cdpr.ca.gov/docs/emon/grndwtr/gwpa_shapefiles.htm. California Department of Public Health. 2013a. California Environmental Health Tracking

Program, Public Water Systems Boundary Tool, http://www.ehib.org/page.jsp?page_key=762. California Department of Public Health. 2013b. Water quality analyses database files.

http://www.cdph.ca.gov/certlic/drinkingwater/Pages/EDTlibrary.aspx. California Department of Water Resources (DWR). 2003. California’s groundwater. DWR

Bulletin 118 http://www.water.ca.gov/groundwater/bulletin118/san_joaquin_river.cfm California Department of Water Resources. Land and water use data. Unpublished. California Department of Water Resources (DWR). no date shown. A preliminary assessment of

salt-affected soils in the San Joaquin Valley. Map. Data Sources: USDA NRCS, SSURGO. California State Water Resources Control Board. 1999/2011. Hydrogeologically vulnerable areas

map (references appear to be 1999 or earlier; map noted as updated March 10, 2011). California State Water Resources Control Board. 2013a. Water quality goals online database.

http://www.waterboards.ca.gov/water_issues/programs/water_quality_goals/search.shtml. Central Valley Regional Valley Water Quality Control Board. 2012. Irrigated Lands Regulatory

Program http://www.swrcb.ca.gov/rwqcb5/water_issues/irrigated_lands/index.shtml. Central Valley Region, California Regional Water Quality Control Board. 2015. Order R5-2015-0095. Waste discharge requirements general order for growers in the Grassland Drainage Area. July 31, 2015. CH2M Hill. 1988. San Joaquin Valley hydrologic and salt load budgets. A report prepared for the San Joaquin Valley Drainage Program, Sacramento, California. Croft, M. G. 1972. Subsurface geology of the Late Tertiary and Quarternary water-

bearing deposits of the southern part of the San Joaquin Valley, California: U.S. Geological Survey Water-Supply Paper 1999-H.

. Davis, G. H., J.H. Green, S.H. Olmstead, and D.W. Brown. 1959. Ground water conditions and

storage capacity in the San Joaquin Valley, California. U.S. Geological Survey Water Supply Paper No. 1469, 287 p.


Davis, G.H., and T.B. Coplen. 1989. Late Cenozoic palehydrology of the western San Joaquin Valley, California, as related to structural movements in the Central Coast Ranges: Geological Society of America Special Paper 234, 40 p.

Deverel, S.J. and S.K. Gallanthine. 1989. Relation of salinity and selenium in shallow

groundwater to hydrologic and geochemical processes, western San Joaquin Valley, California. Journal of Hydrololgy 109: 125-149 p.

Deverel, S.J. and J.L. Fio. 1991. Groundwater flow and solute movement to drain laterals,

western San Joaquin Valley, California: 1. Geochemical Assessment. Water Resources Research 27(9), 2233-2246.

Deverel, S.J. and J.L. Fio. 1991. Groundwater flow and solute movement to drain laterals,

western San Joaquin Valley, California: 2. Quantitative hydrologic assessment. Water Resources Research 27(9), 2247-2257.

Dubrovsky, N.M., J.D. Steven, and J.G. Robert 1993. Reprinted from:

Regional Ground-Water Quality. Edited by William M. Alley. New York: Van Nostrand Reinhold.

Dubrovsky, N.M., J.M. Neil, R. Fuji, R.S. Oremland, and J.T. Hollibaugh. 1990. Influence of

redox potential on selenium distribution in ground water, Mendota, western San Joaquin Valley, California. U.S. Geological Survey Open-File Report 90-138.

Eberts, S.M., M.A. Thomas, and M.L. Jagucki. 2013. The quality of our Nation’s water – Factors

affecting public-supply-well vulnerability to contamination - understanding observed water quality and anticipating future water quality. U.S. Geological Survey Circular 1385, 120p.

Entrix. 2009. Grassland Bypass Project, 2010-2019 Environmental Impact Statement and

Environmental Impact Report, Final, August 2009. Faunt, C., R.T. Hanson, K. Belitz, W. Schmid, S. Predmore, D. L. Rewis, and K. McPherson.

2009. Groundwater availability of the Central Valley Aquifer, California. U.S. Geological Survey Professional Paper 1766. http://pubs.usgs.gov/pp/1766/

Gronberg, J.M. and K. Belitz. 1992. Estimation of a water budget for the Central part of the

western San Joaquin Valley, California. U.S. Geological Survey Water-Resources Investigations Report 91-4192, 22 p.

Gronberg, J.M. and N.E. Spahr. 2012. County-level estimates of nitrogen and phosphorus from

commercial fertilizer for the Conterminous United States, 1987–2006. U.S. Geological Survey Scientific Investigations Report 2012-5207, 20 p.

Harradine, F.F. 1950. Soils of Western Fresno County, California: University of

California, Berkeley.


Izbicki, J. A. 1984. Chemical quality of water at 14 sites near Kesterson National Wildlife Refuge, Fresno and Merced Counties, California. U.S. Geological Survey Open-File Report 84-582.

Izbicki, J. A. 1989. Chemical quality of agricultural drainage water tributary to Kesterson

Reservoir, Fresno and Merced counties, California, January and August 1984. U.S. Geological Survey Open-File Report 87-380.

Kratzer, C.R. and R.N. Biagtan. 1997. Determination of travel times in the Lower San Joaquin

River Basin, California, from dye-tracer studies during 1994-1995. U.S. Geological Survey Water Resources Investigations Report 97-4018, 20 p.

Larry Walker Associates, Luhdorff & Scalmanini Consulting Engineers, Systech, PlanTierra,

Kennedy Jenks, Carollo Engineers. 2013. CV-SALTS Initial conceptual model (ICM) technical services, Tasks 7 and 8 – Salt and nitrate analysis for the Central Valley Floor and a focused analysis of Modesto and Kings subregions, final report.

Laudon, J. and K. Belitz. 1989. Texture and depositional history of near-surface alluvial deposits

in the Central Part of the western San Joaquin Valley, California: U.S. Geological Survey Open-File Report 89-235, 19 p.

Mendenhall, W.C., R.B. Dole, and H. Stabler. 1916. Ground water in the San Joaquin Valley,

California. U.S. Geological Survey Water-Supply Paper 398, 310 p. National Research Council. 1993. Groundwater vulnerability assessment, contamination

potential under conditions of uncertainty. National Academy Press, Washington, D.C., 210 p. Accessed December 2000 at URL http: //books.nap.edu/books/0309047994/html.

Nolan, B.T. 2001. Relating nitrogen sources and aquifer susceptibility to nitrate in shallow

ground waters of the United States. U.S. Geological Survey Ground Water Vol. 39, No. 2, 290 p.

Nolan, B.T., K.J. Hitt, and B.C. Ruddy. 2002. Probability of nitrate contamination of recently

recharged groundwaters in the conterminous United States. U.S. Geological Survey Environmental Science & Technology, Vol. 36, No. 10, 2138 p.

Nolan, B.T. and K.J. Hitt. 2006. Vulnerability of shallow groundwater and drinking-water wells

to nitrate in the United States. U.S. Geological Survey Environmental Science & Technology, Vol. 40, No. 24, 7834.

Page, R.W. 1973. Base of fresh ground water (approximately 3,000 micromhos) in the San

Joaquin Valley, California: U.S. Geological Survey Hydrologic Investigations Atlas HA-489, 1 sheet, scale 1:500,000.

Page, R.W. 1986. Geology of the fresh groundwater basin of the Central Valley, California, with

texture maps and sections: U.S. Geological Survey Professional Paper 1401-C, 54 p.


Phillips, S.P. and K. Belitz. 1991. Calibration of a texture-based model of a ground-water flow

system, western San Joaquin Valley, California: U.S. Geological Survey Ground Water, Vol. 39, No. 5, 702-715 p.

Presser, T. S. and S. E. Schwarzbach. 2008. Technical analysis of in-valley drainage

management strategies for the western San Joaquin Valley, California. U.S. Geological Survey, Open-File Report 2008-1210, 37 p. [http://pubs.usgs.gov/of/2008/1210/].

Rauschkolb RS. Mikkelsen DS. 1978. Survey of fertilizer use in California — 1973. UC

Division of Agricultural Sciences Bulletin 1887, 25 p. RMC. 2014. Westside-San Joaquin Integrated Water Resources Plan-Draft, prepared for San

Luis & Delta-Mendota Water Authority, July 2014, 148 p. Rosenstock, T.S., D. Liptzin, J. Six, and T.P. Tomich. 2013. Nitrogen fertilizer use in California:

Assessing the data, trends and a way forward: California Agriculture, Vol. 67, No. 1, 68 p. San Joaquin Valley Drainage Program. 1990. A management plan for agricultural subsurface drainage and related problems on the Westside San Joaquin Valley, Final Report. Troiano, J., B. Johnson, S. Powell, and S. Schoenig. 1992. Profiling areas vulnerable to

groundwater contamination by pesticides in California. Final Report to the State of California Environmental Protection Agency, Department of Pesticide Regulation, EH 92-09.

Troiano, J., J. Marade, and F. Spurlock. 1999a. Empirical modeling of spatial vulnerability

applied to a norflurazon retrospective well study in California. Journal of Environmental Quality Vol. 28, 397 p.

Troiano, J., F. Spurlock, and J. Marade. 1999b. Update of the California vulnerability soil

analysis for movement of pesticides to groundwater: October 14, 1999. State of California Environmental Protection Agency, Department of Pesticide Regulation.

Troiano, J., F. Spurlock, and J. Marade. 2000. Update of the California soil analysis for

movement of pesticides to groundwater: October 14, 1999. State of California Environmental Protection Agency, Department of Pesticide Regulation, EH 00-05.

USDA NASS. 2014. National agricultural statistics service surveys: agricultural chemical use program. www.nass.usda.gov/Surveys/Guide_to_NASS_Surveys/Chemical_Use/index.asp (accessed May 28, 2014). Williamson, A.K., D. E. Prudic, and L. A. Swain. 1989. Ground-water flow in the Central Valley, California. U.S. Geological Survey Professional Paper 1401-D, 127 p.


Preliminary List of Potential Data Sources

Data Type Database Source

Source Location or Description

Slope/DEM USGS National Elevation Dataset (NED)

http://ned.usgs.gov/

Hydrogeology/Recharge

Central Valley Hydrologic Model (CVHM)

http://ca.water.usgs.gov/projects/central-valley/central-valley-hydrologic-model.html

Published hydrogeology literature

Important publications on hydrogeology of area; USGS mapping data

Soils Natural Resources Conservation Service (NRCS)

http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm

Tile Drain Locations

GDA Districts, USBR, DWR Readily available tile drain location data

Water Level

DWR: Water Data Library http://www.water.ca.gov/waterdatalibrary/

DWR: California Statewide Groundwater Elevation Monitoring (CASGEM)

http://www.water.ca.gov/groundwater/casgem/

SWRCB GeoTracker http://geotracker.waterboards.ca.gov/data_download_by_county.asp

USGS: National Water Information System

http://waterdata.usgs.gov/nwis

Local Entities (e.g. GDA Districts)

Personal Communications

Groundwater Quality – TDS/Nitrate/ Pesticides

USGS: National Water Information System

http://waterdata.usgs.gov/nwis

CDPH http://www.cdph.ca.gov/certlic/drinkingwater/Pages/Monitoring.aspx

Geotracker GAMA http://geotracker.waterboards.ca.gov/gama/

RWQCB (WDR Dairy Data) San Joaquin Valley Data: SWRCB Region 5 office, Fresno, CA.

DWR: Water Data Library http://www.water.ca.gov/waterdatalibrary/

County health departments Readily available domestic well water quality data

California Department of Pesticide Regulation (DPR)

Environmental Monitoring Branch, Sacramento, CA

Local Entities (e.g. GDA Districts)

Personal Communications

Land Use/Crop

GDA Districts Existing data as available from Districts

DWR www.water.ca.gov/landwateruse/lusrvymain.cfm

USDA http://www.nass.usda.gov/research/Cropland/SARS1a.htm CDFA http://www.cdfa.ca.gov/is/ffldrs/frep/index.html County agricultural departments Crop reports and other readily available data UC Cooperative Extension www.ucanr.edu USBR Existing readily available data

Where Addressed in

GAR Outline

1. ObjectivesA. Provide an assessment of all readily available, applicable and relevant data and information to determine

the high and low vulnerability areas where discharges from irrigated lands may result in groundwater

quality degradation.Throughout

B. Establish priorities for implementation of monitoring and studies within high vulnerability areas.

Sections 6 & 7

C. Provide a basis for establishing monitoring workplans to assess groundwater quality trends. Throughout

D. Provide a basis for establishing management practices evaluation program workplans and priorities to

evaluate the effectiveness of agricultural management practices to protect groundwater quality. Throughout

E. Provide a basis for establishing groundwater quality management plans in high vulnerability areas and

priorities for implementation of those plans.Throughout

2. ComponentsA. Detailed land use information with emphasis on land uses associated with irrigated agricultural

operations. The information shall identify the largest acreage commodity types in the Grassland Drainage

Area (GDA), including the most prevalent commodities comprising up to at least 80% of the irrigated

agricultural acreage in the GDA.

Section 4

B. Information regarding depth to groundwater, provided as a contour map(s). Section 3

C. Groundwater recharge information, including identification of recharge areas for urban and rural

communities where groundwater serves as a significant source of supply. Disadvantaged communities

must be identified.

Sections 3 and 5

D. Soil survey information, including significant areas of high salinity, alkalinity and acidity. Section 3

E. Shallow groundwater constituent concentrations from existing monitoring networks (potential

constituents of concern include any material applied as part of the agricultural operation, including

constituents in irrigation supply water [e.g., pesticides, fertilizers, soil amendments, etc.] that could

impact beneficial uses or cause degradation).

Section 5

F. Information on existing groundwater data collection and analysis efforts relevant to this Order (e.g.,

Department of Pesticide Regulation [DPR], United States Geological Survey [USGS], State Water Board

Groundwater Ambient Monitoring and Assessment [GAMA], State Water Board Division of Drinking

Water (formerly CDPH), local groundwater management plans, etc.). This groundwater data compilation

and review shall include readily accessible information relative to the Order on existing monitoring well

networks, individual well details, and monitored parameters. For existing monitoring networks (or

portions thereof) and/or relevant data sets, the Grassland Basin Drainage Steering Committee should

assess the possibility of data sharing between the data‐collecting entity, the Steering Committee, and the

Central Valley Water Board.

Sections 5 & 7

3. Data Review and Analysis of Existing Federal, State, County, and Local Databases and DocumentsA. Determine where known groundwater quality impacts exist for which irrigated agricultural operations

are a potential contributor or where conditions make groundwater more vulnerable to impacts from

irrigated agricultural activities.Sections 5 & 6

B. Determine the merit and feasibility of incorporating existing groundwater data collection efforts, and

their corresponding monitoring well systems for obtaining appropriate groundwater quality information

to achieve the objectives of and support groundwater monitoring activities under this Order. This shall

include specific findings and conclusions and provide the rationale for conclusions.

Section 7

C. Prepare a ranking of high vulnerability areas to provide a basis for prioritization of workplan activities,

with emphasis on communitiies reliant on groundwater as a significant source for water supply and

higher priority given to disadvantaged communities.

Section 6

D. The GAR shall discuss pertinent geologic and hydrogeologic information for the Grassland Drainage Area

and utilize GIS mapping applications, graphics, and tables, as appropriate, in order to clearly convey

pertinent data, support data analysis, and show results.

Sections 3, 5 & 6

4. Groundwater Vulnerability DesignationsA. Designate high/low vulnerability areas for groundwater in consideration of high and low vulnerability

definitions provided in Attachment E of the Order.Section 6

B. The vulnerability designations will be made by using a combination of physical properties (soil type,

depth to groundwater, known agricultural impacts to beneficial uses, etc.) and management practices

(irrigation method, crop type, nitrogen application and removal rates, etc.). Section 6

C. Provide the rationale for proposed vulnerability determinations. Section 6

5. Considerations for Prioritization of High Vulnerability Groundwater AreasA. Identified exceedances of water quality objectives for which irrigated agriculture waste discharges are

the cause, or a contributing source. Sections 5 & 6

B. The proximity of the high vulnerability area to areas contributing recharge to urban and rural

communities where groundwater serves as a significant source of supply.Sections 3 & 6

C. Existing field or operational practices identified to be associated with irrigated agriculture waste

discharges that are the cause, or a contributing source (i.e., practices as currently known and available). Sections 4 & 6

D. The largest acreage commodity types comprising up to at least 80% of the irrigated agricultural acreage

in the high vulnerability areas and the irrigation and fertilization practices employed by these

commodities.Sections 4 & 6

E. Legacy or ambient conditions of the groundwater. Sections 5 & 6

Groundwater basins currently or proposed to be under review by CV‐SALTS.

F. Identified constituents of concern, e.g., relative toxicity, mobility. Sections 5 & 6

Grassland Drainage Area GAR Outline

GAR Items Identified in Monitoring and Reporting Program (Attachment B) of the

Grassland Drainage Area WDR General Order

Cross‐Reference Table between GAR Outline and WDR General Order R5‐2015‐0095

§̈¦5

WESTSIDESUBBASIN

KINGSSUBBASIN

CHOWCHILLASUBBASIN

MADERASUBBASIN

DELTA-MENDOTASUBBASIN

PANOCHE VALLEYGW BASIN

Location Map and DWR Groundwater BasinsGrassland Drainage Area

0 4

Scale in Miles

±

Data sourcesCA Department of Water Resources

MAP EXPLANATIONGrassland Drainage Area

DWR Groundwater Basin/Subbasin

Grasslands GAR Outline Revised 10 16 2015 conjunctively involve reuse of tile drainage to ......

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